IP Address Privacy Considerations
draft-ip-address-privacy-considerations-00
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Matthew Finkel , Authors TBD | ||
| Last updated | 2021-07-12 | ||
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draft-ip-address-privacy-considerations-00
Network Working Group M. Finkel
Internet-Draft The Tor Project
Intended status: Informational T. BD
Expires: 13 January 2022 TBD
12 July 2021
IP Address Privacy Considerations
draft-ip-address-privacy-considerations-00
Abstract
This document provides an overview of privacy considerations related
to user IP addresses. It includes an analysis of some current use
cases for tracking of user IP addresses, mainly in the context of
anti-abuse. It discusses the privacy issues associated with such
tracking and provides input on mechanisms to improve the privacy of
this existing model. It then captures requirements for proposed
'replacement signals' for IP addresses from this analysis. In
addition, existing and under-development techniques are evaluated for
fulfilling these requirements.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the mailing list (), which
is archived at .
Source for this draft and an issue tracker can be found at
https://github.com/ShivanKaul/draft-ip-address-privacy.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 13 January 2022.
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Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IP address tracking . . . . . . . . . . . . . . . . . . . . . 4
3.1. IP address use cases . . . . . . . . . . . . . . . . . . 4
3.1.1. Anti-abuse . . . . . . . . . . . . . . . . . . . . . 4
3.1.2. DDoS and Botnets . . . . . . . . . . . . . . . . . . 4
3.2. Privacy implications of IP addresses . . . . . . . . . . 4
3.3. Mitigations for IP address tracking . . . . . . . . . . . 4
4. Replacement signals for IP addresses . . . . . . . . . . . . 5
4.1. Requirements . . . . . . . . . . . . . . . . . . . . . . 5
4.1.1. Client requirements . . . . . . . . . . . . . . . . . 5
4.1.2. Server requirements . . . . . . . . . . . . . . . . . 5
4.2. Evaluation of existing technologies . . . . . . . . . . . 6
4.3. Potential new technologies . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The initial intention of this draft is to capture an overview of the
problem space and research on proposed solutions. The draft is
likely to evolve significantly over time and may well split into
multiple drafts as content is added.
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Tracking of user IP addresses is common place on the Internet today,
and is particularly widely used in the context of anti-abuse, e.g.
anti-fraud, DDoS management, child protection activities. IP
addresses are currently used as a source of "reputation" in
conjunction with other signals to protect against malicious traffic,
since they are a relatively stable identifier of the origin of a
request. Servers use these reputations in determining whether or not
a given packet, connection, or flow corresponds to malicious traffic.
However, identifying the activity of users based on IP addresses has
clear privacy implications e.g. user fingerprinting and cross site
identity linking. Many technologies exist today to allow users to
hide their IP address to avoid such tracking, e.g. VPNs, Tor.
Several new technologies are also emerging in the landscape e.g.
Gnatcatcher, Apple iCloud Private Relay and Oblivious techologies
(OHTTPS, ODoH).
This draft attempts to capture the following aspects of the tension
between valid use cases for user identification and the related
privacy concerns including:
* An analysis of the current use cases, attempting to categorize/
group such use cases where commonalities exist
* Find ways to enhance the privacy of existing uses of IP addresses.
* Generating requirements for proposed 'replacement signals' from
this analysis (these could be different for each category/group of
use cases)
* Research to evaluate existing technologies or propose new
mechanisms for such signals
2. Terminology
(Work in progress)
* Reputation: A random variable with some distribution. A
reputation can either be "bad" or "good" with some probability
according to the distribution.
* Reputation signal: A representative of a reputation.
* Reputation proof: A non-interactive zero knowledge proof of a
reputation signal.
* Reputation context: The context in which a given reputation
applies.
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* Identity: Any identifying information about an end-user or
service, be it a client or server, including IP addresses.
3. IP address tracking
3.1. IP address use cases
3.1.1. Anti-abuse
Account abuse, financial fraud, ad fraud, child abuse...
3.1.2. DDoS and Botnets
3.2. Privacy implications of IP addresses
IP addresses provide a relatively stable identifier
(https://hal.inria.fr/hal-02435622), and are an important attribute
in tracking people as they load web pages across sites. While the
stable identifier is important in the above anti-abuse cases, this
fact threatens a user's privacy because it allows for profiling of
behavior. This profiling may occur anywhere on the path between the
client and the server, inclusive. In addition, IP addresses
passively leak meta information about the user, such as their rough
geographical location. This may be beneficial, but not always as the
default.
Some mitigations are discussed below, however any holistic solution
must ensure privacy is available with no additional cost.
3.3. Mitigations for IP address tracking
The ability to track individual people by IP address has been well
understood for decades. Commercial VPNs and Tor are the most common
methods of mitigating IP address-based tracking.
Commerical VPNs offer a layer of indirection between the user and the
destination, however if the VPN endpoint's IP address is static then
this simply substitutes one address for another. In addition,
commerial VPNs replace tracking across sites with a single company
that may track their users' activities.
Tor is another mitigation option due to its dynamic path selection
and distributed network of relays, however its current design suffers
from degraded performance. In addition, correct application
integration is difficult and not common.
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Recent interest has resulted in new protocols such as Oblivious DNS
(ODoH (https://www.ietf.org/staging/draft-pauly-oblivious-doh-
02.html)) and Oblivious HTTP (OHTTP (https://www.ietf.org/archive/id/
draft-thomson-http-oblivious-00.html)). While they both prevent
tracking by individual parties, they are not intended for the
general-purpose web browsing use case.
Finally, Gnatcatcher (https://github.com/bslassey/ip-
blindness/blob/master/README.md) is a single-hop proxy providing more
protection than a traditional commercial VPN; and iCloud Private
Relay is described as using two proxies and would provide a level of
protection somewhere between a commercial VPN and Tor.
4. Replacement signals for IP addresses
Fundamentally, the current ecosystem operates by making the paths of
a connection accountable for bad traffic, rather than the sources of
the traffic itself. This is problematic because in some cases IP
addresses are shared by multiple clients (e.g., VPNs, Tor, carrier-
grade NATs (CGNATs)) and any misbehavior may be impermanent.
Ideally, clients could present proof of reputation that is separate
from the IP address, and uniquely bound to a given connection.
4.1. Requirements
4.1.1. Client requirements
* Clients MUST be able to request and present new reputation proofs
on demand.
* A reputation signal MUST NOT be linkable to an Identity for which
the signal corresponds.
* Clients MUST be able to demonstrate good faith and improve
reputation if needed.
* Clients MUST be able to dispute their reputation.
* Clients MUST be able to determine and verify the context in which
a given reputation applies.
* Reputation signals MUST NOT remain valid indefinitely. (Clients
must obtain new reputation signals periodically.)
4.1.2. Server requirements
* Reputation signals MUST be bound to a context, and MUST NOT be
transferrable across contexts.
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* Clients MUST NOT be able to transfer reputations.
4.2. Evaluation of existing technologies
4.3. Potential new technologies
5. Security Considerations
TODO
6. IANA Considerations
This document has no IANA actions.
Acknowledgments
TODO
Authors' Addresses
Matthew Finkel
The Tor Project
Email: sysrqb@torproject.org
Authors TBD
TBD
Email: tbd@tbd.com
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